三江平原沼泽土中多环芳烃分布及火烧的影响

Distribution of Polycyclic Aromatic Hydrocarbons in Marsh Soils from the Sanjiang Plain and Fire Effect on It

为了研究三江平原沼泽土中多环芳烃(PAHs)的分布,采用气相色谱—质谱法(GC-MS)对沼泽土中16种优控多环芳烃污染物进行分析。结果表明,该区沼泽土中共检测出萘、苊烯、苊、芴、菲、蒽、荧蒽和芘8种PAHs,其总含量为365.4～975.4ng/g,平均值为(850.7±126.2)ng/g。与中国东北其他地区沼泽土相比,其低于长白山和大兴安岭摩天岭雨养泥炭沼泽土中的PAHs含量。检测出的PAHs以低环为主,在不同成分中萘、芴、菲的含量较高;不同采样点中,有火烧迹象沼泽土中的PAHs含量高于无火烧迹象的沼泽土。为验证火烧的影响,进行了土壤热处理后PAHs变化的试验,结果显示,经热处理后的沼泽土中PAHs的总量及各成分的含量均高于未经热处理的沼泽土。火烧是影响三江平原沼泽土中PAHs含量的重要因素之一。

Wetlands ecosystem is quite frangible;the influence produced by polycyclic aromatic hydrocarbons（PAHs）is very evident.However,researches about PAHs contamination in wetlands ecosystem mostly focus on the lakes and the mangroves but have largely overlooked the marshes.The Sanjiang Plain,which has the largest freshwater marshes in China,has experienced intensive cultivation over the past 50 years.The major soil types were meadow marsh soil,humus marsh soil and peat marsh soil.However,there were few reports about PAHs in marsh soils in this area.In order to reveal the effect of fire on the distribution of PAHs in the marsh soils,the distributions of PAHs in marsh soils from 5 sites in the Sanjiang Plain have been investigated and analyzed.A heating experiment in the laboratory was conducted to determine the effect of heating on PAHs.About 10 g marsh soil was heated in muffle furnace at 340 ℃ for 1 hour.After cooling to the room temperature,the PAHs contents in the heated marsh soil were analyzed by gas chromatography-mass spectrometer（GC-MS）.In unheated marsh soils,the total concentrations of PAHs ranged from 365.4 ng/g to 975.4 ng/g,with the average of（850.7 ± 126.2）ng/g.Whilst in the heated marsh soils,the total contents of PAHs ranged from 910.6 ng/g to 4 325.1 ng/g,with the average of（2 493.3 ± 569.1）ng/g,In comparison with other marshes in Northeast China,the contents of PAHs in the marsh soils were lower than those in ombrotopic marsh soils in om-brotrophic bog in Greater Hinggan Mountains and ombrotopic marsh soils of Changbai Mountains.The 2-3 rings compounds were the dominants PAHs in the region,and 5-6 rings PAHs were not detected.It suggested that there were no source of the high rings＇PAHs in the region.The 8 types of PAHs determined in this study were naphthalene,acenaphthylene,acenaphthene,fluorene,phenanthrene,anthracene,fluoranthene and pyrene.A-mong of them,naphthalene,fluorene and phenanthrene are were the dominants.During the 5 sites,the sites which had been firedsites that had been fired have more PAHs than that those without fire.It suggested that fire affected the distribution and concentrations of PAHs in the marsh soils.Furthermore,the contents of PAHs in the heated marsh soils were greater than those in the marsh soils without heating experiment.The greater level of PAHs in heated marsh soils showed that fire did play an important role in the PAHs distribution in marsh soils in the Sanjiang Plain.